This invention relates to polyamides having improved dyeability with acid dyes and more particularly to highly-dyeable, stabilized copolyamides.
It is well known that polyamides prepared using hexamethylene diammonium adipate can be polymerized to high molecular weight and that they can be dyed with acid dyes, but it has been found that it is difficult to obtain very deep shades. Consequently, there has been a continuous search for deep-dyeing polyamide compositions. British Pat. No. 1,077,992 discloses that N,N'-di(3-aminopropyl)-piperazine can be used to improve polyamide dyeability. In U.S. Pat. No. 3,078,248, it is disclosed that the frequency of spinning drips can be reduced in the production of polyamide fibers having improved dyeability from high amine ends by the use of phosphorous compounds such as phenylphosphinates. In the preparation of high relative viscosity polyamides, high levels of amine ends aggravate the problem of gel formation.